PART VI. Striking Errors:

Die Caps:

Partial (off-center) Die Caps:

Definition: A partial die cap begins with a coin that is struck off-center and sticks to either the hammer die or the anvil die.  It is then struck into the next planchet, leaving an “aligned” partial brockage (see aligned partial brockage).  Partial die caps involving the hammer die are much more common than those involving the anvil die,since the latter tend to be scraped off by the ejection finger or lifted up by the top of the collar.

PART VI. Striking Errors:

Off Center Strikes:

Uniface

Definition: An off-center strike in which the coin is struck against an underlying or overlying planchet.  The second situation happens less often.  In either case, the face struck against the planchet is featureless; the opposite face is die-struck.  In an off-center uniface strike, the entire face must be featureless.  If any of it is die-struck, it is designated an off-center strike with indent.

Due to the double thickness involved in such an error, effective striking pressure is elevated.  This often produces a “stretch strike” — a coin with an expanded “slide zone”.

PART VI. Striking Errors:

Off Center Strikes:

With Collar Scar

Definition:  An off-center strike will often show a collar scar on the face struck by the anvil die.  A collar scar is a semi-circular groove that lies lateral to the die-struck design and the location of the design rim.  The collar scar is produced when the protruding portion of the off-center planchet is forced down upon the top of the collar by the descending hammer die.  The strength and completeness of the collar scar varies considerably, and a significant fraction of off-center strikes show no collar scar at all.

The above off center struck 1998-P Washington quarter has collar scars on the reverse of the coin (indicated by the black arrows).

The above undated Jefferson nickel shows a small area of where the collar indented the planchet (indicated by the black arrow).

Part VI. Striking Errors:

Off-center Strikes:

Cupped Off-center Strikes

Definition:  As is the case with broadstrikes, off-center strikes can show degrees of cupping ranging from nil to 90 degrees.  In many cases there’s no obvious cause for the cupping.  In other cases, the unstruck portion of the planchet is forced up by a stiff collar.

PART VI. Striking Errors:

Multiple strikes: 

On-center/Off-center

Definition: Multiple strikes can be either on-center or off-center. The reasons for multiple strikes are as varied as the number of strikes that can occur. Ejection failures which prevent a planchet to correctly discharge from the striking chamber are numerous.

A 1985 10 pesos from Argentina which has been struck off-center a minimum of 17 times. This coin was highly distorted by several other planchets entering the striking chamber. Complete details of each strike were obliterated by these intruding planchets.

PART VI. Striking Errors:

Edge Strike:

Off-center or Broadstrike Produced by Continuation

of the Down Stroke

Definition: An edge strike is a coin struck on-edge.  It may have entered the striking chamber spinning on its edge.  It may have been kicked up into a vertical position by the insertion finger.  It may have entered the striking chamber rolling along on its edge.  Or it may have been flying through space and managed to get caught by the descending hammer die.

After initial contact, an edge-struck planchet slips and falls on its side.  During this phase it is often kicked out of the striking chamber.  The impact on the edge may cause the planchet to bend.  The presence and severity of the bend is highly variable. The reason the planchet slips may be because it might have not have been perfectly vertical or it might have been sitting in a sloping recess of the die face that caused it to slip.  In either case, folding is not complete.  If it was, the coin would have been converted into a foldover strike (see foldover strike).

An edge strike can appear at both poles of an otherwise unstruck planchet.  A coin can receive a second strike that also happens to be an edge strike.  Sometimes an edge-struck planchet slips and lands on its side within the striking chamber.  It then receives a conventional strike (centered or off-center) during the completion of the  downstroke of the hammer die.  The last eventuality is illustrated here by a 1986 cent.

Part V. Planchet Errors:

Wrong Planchet and Off-Metal Errors:

Double Denomination Errors:

Struck Over Pre-Existing Wrong Planchet/Off-Metal Error

Definition: A design struck over another design (either domestic or foreign) which was, in turn, struck on the wrong planchet.  Such errors are quite rare, with a significant proportion intentionally fabricated inside the mint.

This state quarter design was struck over a 2000-P nickel design which had been, in turn, struck twice on a cent planchet.  The quarter strike was off-center and has a first-strike brockage of the obverse quarter design on its reverse face.  This error may have had some assistance in its creation.  Photos courtesy of Terry Holcomb.

This 2004 Canadian cent design was struck over a 2004 Papua New Guinea 1 tohea design which had itself been struck on a Fiji one cent planchet.  The coin was cherrypicked from eBay by James Zimmerman, who expended a great deal of time and effort in identifying the host coin design and the original purpose of the planchet.  This seems to be a truly accidental error.  Photos courtesy of James Zimmerman.

This 1983 Canadian cent design was struck on an Israel 10 shekels design which was originally struck on a Canadian 1 cent planchet.  As such, the final strike generated a dual country / double-denomination error but not a wrong planchet error.  This is almost certainly an intentional error because it was struck in-collar.  The original off-metal coin would have to have been resized after the first strike, which would have caused the coin to expand beyond the diameter of the collar.  Photos courtesy of Fred Weinberg.

This 1982 Costa Rica 25 centavos design was struck over an Israel 10 shekels design which had originally been struck on a Costa Rica 25 centavos planchet.  As with the previous coin, the final strike generated a dual country/double denomination error but not a wrong planchet error.  And as with the previous coin, the last strike was in-collar, which would have required resizing of the expanded off-metal 10 shekels.  Photos by Mike Diamond

PART V: Planchet Errors:

Wrong Planchet and Off Metal Errors

Definition: A wrong planchet error is exactly what the name indicates – a coin struck on a planchet intended for another denomination (domestic or foreign).  The incorrect planchet may have the same composition (e.g. a quarter struck on a dime planchet) or it may be a different composition (e.g., a quarter struck on a nickel planchet).

An off-metal error is a coin struck on a planchet whose composition does not match the composition that normally characterizes the coin.  While off-metal errors can be wrong planchet errors, this is not always the case.  For example, a dime struck on a copper core is off-metal but is not really a wrong planchet.

.

A Sacagawea planchet somehow found its way into the coin press that was striking  1999-P Susan B. Anthony dollars.

This coin is comes to us courtesy of Mark Lighterman

Images were taken through an encapsulation.

Part V: Planchet Errors:

Wrong Stock:

Off-Metal

Photos courtesy of Heritage Auctions.

PART V. Planchet Errors:

Bonding / Bonding Mill Errors:

Struck Clad Layer:

Split Off After Strike

Definition: A clad layer will sometimes separate from a coin after the strike.  The detached clad layer will show a normal die-struck design on its outer face, and blurred incuse, mirror-image version of the same design on its inner face.

As a practical matter, it is almost impossible to distinguish this error type from clad layers that are struck together with a normal planchet.

An undated clad layer from a Roosevelt dime is shown below. It may have separated after the strike or it may have been fed into the striking chamber beneath a normal planchet.